The present invention relates generally to semiconductor device manufacturing, and more particularly to a structure and method for fabricating a silicide on a device using laser annealing.
The use of silicides is well known in the field of semiconductor manufacturing. A silicide is a silicon metal alloy, typically composed of a transition metal including, for example, nickel (Ni), platinum (Pt), palladium (Pd), titanium (Ti), tungsten (W), tantalum (Ta), cobalt (Co), or alloys thereof. Silicides are commonly used to provide low resistivity structures for contacting the gate electrode and the source-drain electrodes in metal oxide semiconductor (MOS) devices. The transition metals have many desirable characteristics for use in silicides: they exhibit low electrical resistivity, react with silicon at relatively low temperatures, and do not react with most dielectrics.
Unfortunately, none of the transition metals are ideal for every application. For example, using nickel silicide (NiSi) in source-drain regions can be problematic because nickel silicide can spike (i.e., continue to react past a desirable point) to form NiSi2 in p+ active regions, as well as encroach under gate spacers and gate electrodes. Even variations in the concentration of a metal in a silicide can cause problems in a device. For example, while a nickel silicide containing, for example, 10 atomic percent of platinum (Ni0.90Pt0.10), is suitable for use in one device, such as logic transistors, it can create leakage issues in another device, such as an eDRAM access transistor, as a result of thermal annealing steps used during the back end of the line (BEOL) processing of the chip. Conversely, while a silicide containing an increased concentration of platinum, for example, 15 atomic percent of platinum (Ni0.85Pt0.15), can be suitable for eDRAM access transistors, it can create some silicide encroachment issues on logic transistors.
Typically, these issues are circumvented by forming multiple silicides on a device. Common techniques used to form multiple silicides on a single structure can involve depositing an insulating layer and a hardmask over a specific region to prevent silicide formation in that region, or using a selective etch to expose a specific region for silicide formation. These techniques can require multiple processing steps that can cause defects in the multiple silicides. Accordingly, it may be desirable to overcome the deficiencies and limitations described hereinabove.